Sludge digestion chamber



Mach 3, 1936. M. PRUSS SLUDGE DIGESTION CHAMBER Filed Jan. 15, 1932 y zlfezzfaf.-

,'tation by the sludge.

kPatented Mar. 3, 1936 UNITED ,STATES-K PATENT GFFICE Application January 15, 1932, serial No. 586,938

In Germany January 15, 1931 6 Claims.

The present invention relates to chambers -serving 'for the decomposition of sludge and has more particularly reference to means for directly heating such chambers. I

In order to directly heat sludge digestion chambers heating coils have been provided hitherto rigidly mounted in the chamber. This arrangement, however, suiers from the drawback that only low water temperatures can be employed owing to the fact that with higher temperatures the sludge sticks to the heating pipes and prevents further passage of the heat. Furthermore, cleaning of the pipes and their attendance is only possible after complete emptying of the chamber and expulsion of the gases. Because of the long germination period of a digestion chamber, especially with small installations that comprise only one chamber, these operations result in serious disadvantages as they prevent continuous operation so that this mode of heating is employed only rarely. i

`It has further been proposed to interpose a heating device in the pressure pipe of a sludge circulating pump disposed outside the digestion chamber. In such an arrangement, however, the heating device is exposed tocorroslon and incrus- Therefore an indirect heating of the chamber has been proposed by introducing. hot water immediately in thesludge or by preheating the fresh sludge to be supplied to the chamber. In the former method a great portion of the heat introduced is lost uselessly with the heating water which is drawn off again while in the other method a special boiler is required for the preheating of the fresh sludge outside of the-digestion chamber which boiler could 'be saved.

if the sludge were heated immediately within the digestion chamber.

Now myKV present invention has for its object means fo'r directly heating the sludge within the digestion chamber and for overcoming all the drawbacks hereinbefore mentioned. I achieve this object by arranging the heating device in such 'a manner that it hangs freely in the chamber and can be removed independently of the cover thereof.

In order to obtain a' satisfactory circulation of the sludge water past the heating device, my invention further comprises the arrangement of the heating bodies within a frame or jacket which projects from above into the digestion chamber dow-n to the liquid level therein and is in communication with the chamber at a point below the liquid level therein. By arranging these communications in superposition, an automatic circulation of the sludge water is obtained, due to` the buoyancy of the hot water, past the heating bodies, the sludge water entering the jacket A through the lower apertures thereof, being heated within the jacket while passing past the heating -bodies and in this preheated state leaving the jacket through the upper apertures. In lieu of this arrangement a positive circulation of the sludge water may be provided by means of a pump which is disposed and operates either so as t0 suck the cold sludge water from the chamber or to press the water preheated by the heating bodies into the chamber. g

Inorder that my invention may beclearly understood and readily carried -into effect, a sludge. digestion chamber is illustrated in the accompanying drawing in a vertical section and shows several embodiments of heating devices designed in accordance with my invention by way of example.

In this drawing a denotes a slud'ge digestion chamber which may have any desired suitable shape.

The fresh sludge is fed to the chamber l through one or more conduits b, while the mature sludge is drawn off periodically through one or morey conduits c, the sludge water displaced by the fresh sludge supplied owing off through a conduit l, 2.

One or more heating appliances are-.disposed design, structure and disposition, the drawing...

illustrating three embodiments only by way of .example.

The embodiment illustrated near the center of chamber a comprises a frame or socket 6 tted in the cover 5 of the chamber and gas-tightly closed by a cover plate 1 to which heating pipes 8 are fixed. The pipes 8 project into the contents ofthe chamber and are connected to a hot water feed conduit '3 and a return conduit 4 so that `hot water or the like is in permanent circulation through `the heating pipes 8. The latter are surrounded at a suitable distance by vertical walls or jackets 9 which terminate at their tgps below the level d of the sludge. At a certain distance below the lower end of the jacket 9 is disposed Ia roof-shaped body'l0. The sludge water enters the jacket 9 from below between the lower; edge thereof and the roof I0, is heated by passing past the pipes 8 and leaves the jacket Sat the top, as indicated by the arrows. During this circulation the roof I0 prevents flocks or cakes of sludge from rising from the lower portion of the chamber and reaching the pipes 8V so that in the extreme case only very small quantities of sludge can deposit` thereon.l When they need to be cleaned the pipes 8 can be withdrawn from the chamber separately or in groups, after removal of cover plate 1, Without interrupting the process of deaccording to the invention is illustrated in the.

left-hand portion of the drawing in which a pump is provided to suck the cold sludge water. I3 denotes the heating body which in this embodiment Vis formed by a hollow cylindrical body connected tothe hot water feed pipe 3 and return pipe 4, as indicated by arrows. extends into-the liquid through a suillciently wide aperture provided in the cover 5 which has an extension forming a jacket I4 and likewise extending into the liquid, the heating cylinderA I3 being surrounded by the jacket I 4. At a certain distance below the latter is arranged again a roof-shaped body III which deilects rising sludge cakes -from the heating cylinder I3. The pressure pipe I2 of a pump II extends intov the heats ing cylinder- I3 through which pipe the cold sludge water is driven through the suction pipe I tinto the free inner space of cylinder I3, this water then rising withinthe latter as indicated by arrows and under the action of the following water ows as heating water over the upper edge of cylinder I3 into the annular space between the mier and jacket u.

In order to feed the hot water to the chamber at a lower point, in lieu of the entrance passages I5 pipes 2 8 indicated in dot and dash lines may be connected to the lower end of jacket I4 throughwhich pipes the water driven by the `pump II into the jacket and heatedtherein enters the di' gestion chamberat a lower level.

Furthermore, instead of disposing the heating body or bodies in the digestion chamber proper. they may be arranged in special chambers separated from the main chamber and communicat` ing therewith by passages.l An example of this arrangement is illustrated in the drawing at the right-hand upper corner of the chamber a. A chamber I1 is separated here by a partition I 6 from the' main digestion chamber and communicates with the latter by a lower passage 24. A

dip pipe I8 is further provided which connects the chamber I1 with the main chamber. In the chamber I1 is arranged a heating body I 9 in'a manner so as to be removed or exchanged from above, which is connected to the ,hot water feed pipe 3 and return pipe 4. Finally, the suction Pipe 2li' of a pump 20 extends into the chamber I1 and serves to suck the sludge water heatedby the body I9 from chamber I1. This water is then driven by the pump through along dip pipe 2| into the lower portion of chamber a. The quantity of water sucked oil by the pump is replaced by a corresponding quantity of cold water which enters chamber I1 through the dip pipe I8 from main chamber a, a partition 22 provided in chamber I1 serving to lead this water to the lower portion of chamber I1. Any sludge which is carried along by the water may be drawn The heating cylinder I3 ofi.' from chamber I1 through a drain pipe 23 or flows automatically` back to chamber a through the passage 2l. It a pipe 23 is provided, the passage 24 may be dispensed with.

The heating and circulating system described above may be modified in so far as the pump Il may be reversed so that hot water is drawn off from chamber I1 through pipe I to chamber a. Inthis case it is of advantage to dispose the pump. Il like the pump 2l of the last-described embodiment immediately above the'suction pipe.

to have the latter as short as possible.

In the event that the water circulation brought about by the pumps does not suilice to lead the warmsludge water collecting at the surface down to the lower portion of` chamber a, axial -pumps 25 may be provided which are driven eachby a motor 26 mounted on`the cover 5 and suck the sludge water from the lower layers to the upper ones through pipesc 21 rigidly fixed in chamber a. In this way-a uniform heating of the whole contents of the digestion chamber is obtained.

What I claim Patent is:-

1. In a digestion plant for the treatment of sludge, which includes a tank in which the sludge is disposed with a layer of supernatant material thereabove, a cover on said tank, heating bodies extending downwardly into the supernatant layer of sludge material and adapted to be removed from the tank independently of the cover, and means for Amixing the whole content of the tank.

2. In a digestion plant for the treatment of and desire to secure by Letters sewage sludge, which includes a tank in which the sludge is disposed with a layer of supernatant material thereabove, a cover on said tank, heating bodies extending downwardly into the supernatant' layer of said sludge material and adapted to be removed from the `tank independently of the4 cover, jackets open at the bottom 'and top and surrounding said heating bodies, said jackets extending from above'into the supernatant layer of said sludge material, said jackets communiveating atvtheir upper and lower ends' with the tank below the level of the said supernatant layer, and means for mixing the whole content of the tank.

3. In adigestion plant as' claimed in claim 2, a pump adapted to circulate the supernatant layer of material past said heating bodies.

4. In a digestion plant as claimed in claim 2, said last means being spaced laterally from said heating bodies.

5.` In a digestion plant as claimed in claim 2, a pump adapted to circulate the upper layer of sewage material past saidheating bodies. and at least one axial pump adapted to assist in circulating said supernatant layer of material.

6. In a digestion plant for the 'treatment of sludge, which includes a tank in which the sludge is disposed with a layer of supernatant material thereabove, a cover on said tank. heating bodiesextending downwardly into the supernatant layer of sludge material and adapted to be removed from the tank independently of the cover, and means for conducting the contents oi the upper part of the tank to the lower part thereof.

7o Max Paiiss. 

